Constant Acceleration involving Suvat Equations ?

Acceleration is always 9.8 unless stated
11) A youth playing in a yard surrounded by a 3 metre-high wall kicks a football vertically upward with initial speed 15m/s
a) What is the greatest height reached by the ball ?
b) For how long can it be seen by someone on the other side of the wall ?

12) A small ball is released from a point 1.6 m above the floor. When it hits the floor its speed is halved. How high does it bounce ?